Improving flowering and vegetative growth in Oncidium baueri Lindl. through gibberellic acid application: insights into physiological parameters

• Published in: Ornamental Horticulture (Campinas) 2024, Vol.30
• Main Authors: Monteiro, Kauê Alexandre, Gonçalves, Gilmar Silva, Bazalha, Carlos Eduardo Orlandini, Paula, Jean Carlo Baudraz, Guariz, Hugo Roldi, Shimizu, Gabriel Danilo, Faria, Ricardo Tadeu
• Format: Article
• Language: eng ; por
• Subjects: AGRONOMY
• ISSN: 2447-536X; 2447-536X
• DOI: 10.1590/2447-536x.v30.e242783

Abstract Plant regulators are studied because they can alter commercially significant aspects of plant growth. Gibberellic acid (GA3) exemplifies this, as it plays a crucial role in the growth and flowering processes of various vegetables. Thus, the present study sought to verify the effects caused by the exogenous application of different doses of the plant regulator GA3 on the floral, vegetative, and physiological patterns of the orchid Oncidium baueri. The experimental treatments (T1; T2; T3; T4; and T5) had 10 replicates, each containing one plant, with the respective sprayed doses: 0, 50, 100, 200, and 400 mg L-1 of GA3. The parameters measured were: pseudobulb length (PL) and width (PW), leaf length (LL), leaf width (LW), number of leaves per plant (NL); time for flower spike to sprout (TFSS), time for flowers to open fully (TFOF), and time for flowers to fall (TFF), these measured in days; flower stem length (FSL), number of flowers per stem (NFS), chlorophyll a fluorescence (fv/fm), and stomatal conductance (G s ). Data were compared using the Tukey test at a significance of 5%. The concentration of 200 mg L-1 of GA3 increased PL and LL by 3 cm on average, and NL showed an increasing trend with treatment 4 compared to doses other than 0 mg L-¹. Regarding floral aspects, this same dose showed the lowest TFSS, distinguishing itself from the other treatments. For physiological parameters, this dose also resulted in higher fv/fm (0.826) and G s (65.340 mmol m-2 s-1). Therefore, the use of 200 mg L-1 of GA3 is recommended for O. baueri plants to optimize vegetative and floral promotion. Resumo Reguladores vegetais são alvos de estudos por terem a capacidade de modificar aspectos de interesse comercial nas plantas. É o caso do ácido giberélico (AG3), um dos hormônios responsáveis pelo crescimento e que está envolvido no processo de floração de muitos vegetais. Dessa maneira, o presente estudo buscou verificar os efeitos causados pela aplicação exógena de diferentes doses do regulador vegetal AG3 nos padrões florais, vegetativos e fisiológicos da orquídea Oncidium baueri. Os tratamentos experimentais (T1; T2; T3; T4; e T5) tiveram 10 repetições, cada uma contendo uma planta, com as respectivas doses pulverizadas: 0, 50, 100, 200 e 400 mg L-1 de AG3. Os parâmetros mensurados foram: comprimento (CP) e largura de pseudobulbo (LP), comprimento e largura de folhas (CF e LF), número de folhas por planta (NF), tempo para emissão de hastes florais (TEHF), tempo p